Manufacture of odorless soap from low grade oils and fats



Patented June 2, 1953 MANUFACTURE OF ODORLESS SOAP FROM LOW GRADE OILS AND FATS Klaus Appuhn, Vina Del Mar, Chile, assignor to Compaiiia Industrial, Valparaiso, Chile, a corporation of Chile No Drawing. Application March 21, 1950, Serial No. 151,030

4 Claims. 1 The present invention relates to the manufacture of good quality, odorless soap from malodorous low grade animal or vegetable oils and fats.

Soaps made from animal and vegetable oils and fats having unsaturated components, aside from having a very soft and slimy consistency, rapidly undergo oxidation and become rancid, rendering the use of such soaps objectionable.

Heretofore all attempts to manufacture odorless soap from malodorous oils and fats have only proven partially practicable since such methods depend upon transforming, either partially or completely, the malodorous unsaturated components into their saturated homologs. To accomplish such transformation two procedures are known; one is by hydrogenation and the other is by following the old Varrentrapp reaction. According to the Varrentrapp reaction, heating oleic acid at high temperature with a slight excess of alkali than is required for its neutralization results in a palmitic acid soap, together with sodium acetate and hydrogen. The equation involved in the Varrentrapp reaction is:

CnHaaCOOH 2NaOH=C15Ha1OOONa CH COONa H,

Oleic acid Sodium palmitate The Varrentrapp reaction is applicable to other unsaturated fatty acids having one or more double bonds and has been the basis for considerable research which established that the yields from such reaction are substantially the theoretical amounts. Because of the high yield numerous attempts have been made to employ said reaction for industrial purposes and the technical literature contains numerous references to such proposed utilization. Among these references are:

The trials made by Oliver and Radisson in treating by batches 1.5 tons of oleic acid with concentrated lye at approximately 300 C. wherein, by splitting the soap produced they obtained palmitic acid of a light brown color. In order to avoid the danger of decomposition from overheating and to maintain the mass of reactants in a liquid state, paraifin was added to the reacting mass (Chem. Industrie 1883, 170).

According to the Persapol method, Stiepel treated water containing soaps made from malodorous fish oils with steam in an autoclave at a temperature above 200 C. until the steam issued from the autoclave in an odorless condition, which happened when the transformation of the unsaturated fatty acids had taken 2 place with the liberation of hydrogen (British patent, No. 145,502). This Persapol method in a sense embodies the Varrentrapp reaction combined with the mechanical deodorization with direct steam. By treatment in an autoclave at 250 C. for six hours a decrease of the iodine number from 118.6 to -84 was obtained in transforming the fatty acids of whale oil into soap, while at 200 C., the decrease of the iodine number was only 96-103.

Schrauth also studied the Varrentrapp reaction and demonstrated that it is possible to obtain saturated fatty acids by heating unsaturated fatty acids with concentrated lye in an autoclave and obtained caprinic acid and probably also some lauric acid after starting with clupanodonic acid, which acid and its homologs, as is well known, give rise to the characteristic fishy smell of whale oil (Fette and Seifen 1943,

In a process of Henkel & Co. (British Patent No. 1'72, 250) a hot whale oil soap containing approximately 60% fatty acid and having an io-' dine number of 130 was pressed through a heated tube at 220 C. and resulted in decreasing the iodine number to -115; then it was pressed through another heated tube at 300 0., thus achieving a greater decrease of the iodine number to 90. When, in addition, 5% of a concentrated lye of 40 B. was added with pressure, it was possible to reduce the iodine number to 80. The pressure inside the tube reached '70 atmospheres, and with such treatment an odorless, light-colored soap was obtained.

In United States Patent No. 2,027,936 (Schrauth) there is disclosed a method of making soap by heating in an autoclave at ZOO-280 C. sperm oil with an excess of concentrated soda lye. In this manner a transformation of the fatty acid of sperm oil into alkali salts of fatty acids is obtained, together with a complete deodorization. In effect, this process embodies a modification of the Varrentrapp reaction although said reaction is not specifically mentioned.

United States Patents Nos. 2,393,421 and 2,492,940 (Schmidt and Edwards) relate to processes for making soap from raw sperm oil and anhydrous alkali employing a predetermined excess of alkali sufficient to saponify the fatty acids and transform the fatty alcohols into soap in a single operation. Here again is an example of a variation of the Varrentrapp reaction without said reaction being expressly mentioned.

The foregoing references from. the literature show that there has been a great deal of interest in finding an industrial application of the Varrentrapp reaction because its advantages over the hydrogenation method of utilizing malodorous fats and oils in the soap industry can be readily appreciated. In fact, the hydrogena tion process is one which demands the use of special and costly installations, special catalysers, and plants for producing highly purified hydrogen, and hence is a rather expensive process.

Moreover, in order that the fats and oils may be properly hydrogenated, previous refining thereof is usually necessary and, when treating malodorous oils and fats, this pre-purifying is all the more important but generally very difficult to accomplish and is attendant with considerable losses. Furthermore, soaps made from hydrogenated fats and oils are very hard, are diflicultly soluble, have poor lathering qualities and can only be used in relatively small percentage in combination with soaps made from other fats.

In contradistinction to the costliness and difficulties involved in the hydrogenation of malodorous oils and fats, the advantages inherent in a correct application of the Varrentrapp reaction in the utilization of malodorous oils and fats readily becomes apparent. Thus, starting with fatty compounds of high molecular weight and more or less highly unsaturated, having carbon chains as C20 and C22, it is possible to tran form such unsaturated compounds into others having a greater degree of saturation as, for example, compounds having carbon chains C14 to C18 andeven C10 to C14, which latter compounds, from the soap industrys point of view, are the most valuable. A further advantage resides in the fact that the same effect of deodorization of fats can be obtained as by hydrogenation, but the soap resultin therefrom is not so hard, is completely soluble in water and possesses high detergent powers.

In View of the teaching of the prior art, and particularly the success achieved in the methods of making soap from sperm oil as disclosed in United States Patents Nos. 2,393,421 and 2,492,940 aforementioned, I have done considerable research in an endeavor to determine the best way to obtain odorless soap from those fats and oils which, by ordinary saponification methods, give soft, slimy and malodorous soaps, and I have found that it is possible to transform such malodorous oils and fats into soap of good quality by a modification of the Varrentrapp reaction above discussed. In this connection I have found that, by reacting the fatty acids of malodorous oils and fats with molten alkali in the absence of water ata temperature of about 300 C. at atmospheric pressure or at slight superatmospheric pressure, the neutralization reaction is very violent on account of its exothermic character and also, because-f the instantaneous evaporation of the water produced during neutralization, considerable foaming takes place, wherefore a number of precautionary measures must be resorted to in order to make the process practicable and industrially profitable. Notwithstanding this, however, I have found that the intensity of the reaction can be moderated to an extent such that it is possible to carry out the reaction in a continuous manner without extraordinary precautions, if to the fatty acids which are being subjected to neutralization there is added sperm oil which, I have found, reduces the violence of the reaction. I have also determined that with a minimum of 40% of sperm oil in the mixture, the aforementioned difficulties can be obviated. I have also 4 determined that as an alternative for sperm oil, Wool grease may be used.

Accordingly, in carrying out my present invention, a mixture of malodorous fatty acids and sperm oil at a temperature slightly above the melting point and molten alkali are charged simultaneously and continuously in predetermined proportions to a specially constructed saponifier where they react at a temperature of about 300 C. The reaction between the fatty matter and the alkali takes place simultaneously and results in complete saponification with the liberation of hydrogen. The apparatus which I employ may be of the type disclosed in United States Patent No. 2,492,9ei0 or any other apparatus operating on substantially the same principle wherein the resultant soap is discharged from the saponifier in a continuous manner by passing through an automatic outlet in substantially the same quantity as the reactants are charged to the saponifier. The hydrogen liberated during the reaction is collected in a manner to maintain a slight superatmospheric pressure within the apparatus, say of not more than 20 cm. of water in order to prevent the entrance of air thereinto. Within the saponification apparatus both exothermic and endothermic reactions take place and, as the heat produced is greater than that consumed, there is a slight excess of heat. In practice it has been found that this slight excess of heat is substantially equal to the heat lost by radiation and hence it is quite simple to maintain a completely uniform temperature within the apparatus with the aid of a small fuel burner in which the consumption of fuel is insigni-ficant. Thus it is possible to obtain an odorless soap of excellent quality in a continuous manner.

The advantages of my process over those previously employed in the making of odorless soap from malodorous fat and oils may be summarized as follows:

(a) No previous refining or hydrogenation of the fats and oils is required.

(1;) The present method does not involve a special treatment of a previously prepared soap, but on the contrary involves the simultaneous saponification and deodorization of fats and oils which may be carried out in a continuous process following the teachings of Patent No. 2,492,940.

(0) The process does not require an autoclave or the generation of high pressures in order to obtain the desired results.

(cl) The process does not require the addition of any fusing agents which are inert during saponification and which would have to be eliminated later.

By sperm oil as used in the specification and claims is meant the oily liquid obtained from sperm whales, whether refined, unrefined or hydrogenated.

What I claim is:

1. A process for the manufacture of odorless soap of good quality which is solid at room temperature, from malodorous unsaturated fatty acids obtained from low grade animal and vegetable fats and oils, said process comprising reacting malodorous unsaturated fatty acids with molten alkali in the absence of Water at substantially atmospheric pressure and in the presence of a reaction moderator capable of reducing the violence of the reaction and the formation of foam, said reaction moderator constituting one of the reactants and being selected from the group consisting of sperm oil and wool grease said reaction moderator constituting at least 40% of the mixture of fatty acids and moderator, the quantity of alkali used being sufficient to completely convert the unsaturated fatty acids and the moderator into an odorless soap having a soap base with a higher degree of carbon atom saturation and a lower molecular weight than the organic reactants.

2. A process according to claim 1 wherein the process is carried out at a temperature between 270 and 330 C.

3. A continuous process for the manufacture of odorless soap of good quality which is solid at room temperature, from malodorous unsaturated fatty acids obtained from low grade animal and vegetable fats and oils, which process comprises reacting in a continuous manner predetermined proportions of preheated malodorous unsaturated fatty acids with molten alkali in the absence of water at substantially atmospheric pressure 2 sperm oil and wool grease said reaction moderator constituting at least 40% of the mixture of fatty acids and moderator, the quantity of alkali being continuously charged being sufficient to completely convert the simultaneously charged unsaturated fatty acids and the moderator into an odorless soap and withdrawing the resultant soap having a soap base with a higher degree of carbon saturation and a lower molecular weight than the organic reactants in a continuous manner.

4. A process according to claim 3, wherein the process is carried out at a temperature between 270 and 330 C.

KLAUS APPUHN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,159,700 Hennig May 23, 1939 2,362,734 Ward Nov. 14, 1944 2,393,421 Schmidt et a1 Jan. 22, 1946 2,492,940 Schmidt et a1. Dec. 27, 1949 

1. A PROCESS FOR THE MANUFACTURE OF ODORLESS SOAP OF GOOD QUALITY WHICH IS SOLID AT ROOM TEMPERATURE, FROM MALODOROUS UNSATURATED FATTY ACIDS ABTAINED FROM LOW GRADE ANIMAL AND VEGETABLE FATS AND OILS, SAID PROCESS COMPRISING REACTING MALODOROUS UNSATURATED FATTY ACIDS WITH MOLTEN ALKALI IN THE ABSENCE OF WATER AT SUBSTANTIALLY ATMOSPHERIC PRESSURE AND IN THE PRESENCE OF A REACTION MODERATE CAPABLE OF REDUCING THE VIOLENCE OF THE REACTION AND THE FORMATION OF FOAM, SAID REACTION MODERATE CONSTITUTING ONE OF THE REACTANTS AND BEING SELECTED FROM THE GROUP CONSISTING OF SPERM OIL AND WOOL GREASE SAID REACTION MODERATE CONSTITUTING AT LEAST 40% OF THE MIXTURE OF FATTY ACIDS AND MODERATE, THE QUANTITY OF ALKALI USED BEING SUFFICIENT TO COMPLETELY CONVERT THE UNSATURATED FATTY ACIDS AND THE MODERATOR INTO AN ODORLESS SOAP HAVING A SOAP BASE WITH A HIGHER DEGREE OF CARBON ATOM SATURATION SAID A LOWER MOLECULAR WEIGHT THAN THE ORGANIC REACTANTS. 